1. Field of the Disclosure
The disclosure relates generally to obtaining core samples from a formation and drilling wellbores in the formation.
2. Description of the Related Art
Oil wells (also referred to as “wellbores” or “boreholes”) are drilled with a drill string that includes a tubular member having a drilling assembly (also referred to as the “bottomhole assembly” or “BHA”) at an end of the tubular member. To obtain hydrocarbons such as oil and gas, wellbores are drilled by rotating a drill bit attached at a bottom end of the drill string. The drill string may include a coring tool with a coring drill bit (or “coring bit”) at the bottom end of a drilling assembly. The coring bit has a through-hole or mouth of a selected diameter sufficient to enable the core sample to enter into a cylindrical coring barrel inside the drilling assembly (coring inner barrel). One or more sensors may be placed around the core barrel to make certain measurements of the core and of the formation surrounding the wellbore drilled to obtain the core. The length of the core sample that may be obtained is limited to the length of the core barrel, which, in an embodiment, may be 600-feet long or longer. Rotation of the coring inner barrel may cause fracturing of the core sample during drilling, thereby reducing or destroying the core's integrity for measurement. Therefore, it is desirable to detect rotation of and maintain a stationary (or non-rotating) state for the coring inner barrel as it receives the core in order to extract a continuous solid and unbroken core sample.